EP0458544A2 - Aide à l'amorçage pour une lampe à forte décharge sans électrodes - Google Patents

Aide à l'amorçage pour une lampe à forte décharge sans électrodes Download PDF

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Publication number
EP0458544A2
EP0458544A2 EP91304473A EP91304473A EP0458544A2 EP 0458544 A2 EP0458544 A2 EP 0458544A2 EP 91304473 A EP91304473 A EP 91304473A EP 91304473 A EP91304473 A EP 91304473A EP 0458544 A2 EP0458544 A2 EP 0458544A2
Authority
EP
European Patent Office
Prior art keywords
starting
arc tube
electrode
arc
lamp
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP91304473A
Other languages
German (de)
English (en)
Other versions
EP0458544A3 (en
Inventor
Sayed-Amr Ahmes El-Hamamsy
Victor David Roberts
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
General Electric Co
Original Assignee
General Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by General Electric Co filed Critical General Electric Co
Publication of EP0458544A2 publication Critical patent/EP0458544A2/fr
Publication of EP0458544A3 publication Critical patent/EP0458544A3/en
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J65/00—Lamps without any electrode inside the vessel; Lamps with at least one main electrode outside the vessel
    • H01J65/04—Lamps in which a gas filling is excited to luminesce by an external electromagnetic field or by external corpuscular radiation, e.g. for indicating plasma display panels
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/16—Circuit arrangements in which the lamp is fed by DC or by low-frequency AC, e.g. by 50 cycles/sec AC, or with network frequencies
    • H05B41/18—Circuit arrangements in which the lamp is fed by DC or by low-frequency AC, e.g. by 50 cycles/sec AC, or with network frequencies having a starting switch
    • H05B41/19—Circuit arrangements in which the lamp is fed by DC or by low-frequency AC, e.g. by 50 cycles/sec AC, or with network frequencies having a starting switch for lamps having an auxiliary starting electrode
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/24—Circuit arrangements in which the lamp is fed by high frequency AC, or with separate oscillator frequency
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/26—Circuit arrangements in which the lamp is fed by power derived from DC by means of a converter, e.g. by high-voltage DC
    • H05B41/28—Circuit arrangements in which the lamp is fed by power derived from DC by means of a converter, e.g. by high-voltage DC using static converters
    • H05B41/288—Circuit arrangements in which the lamp is fed by power derived from DC by means of a converter, e.g. by high-voltage DC using static converters with semiconductor devices and specially adapted for lamps without preheating electrodes, e.g. for high-intensity discharge lamps, high-pressure mercury or sodium lamps or low-pressure sodium lamps
    • H05B41/2881—Load circuits; Control thereof
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/36—Controlling
    • H05B41/38—Controlling the intensity of light
    • H05B41/382—Controlling the intensity of light during the transitional start-up phase
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

Definitions

  • the present invention relates generally to high intensity discharge (HID) lamps. More particularly, the present invention relates to an improved starting aid for an electrodeless HID lamp.
  • HID high intensity discharge
  • HID lamp In a high intensity discharge (HID) lamp, a medium to high pressure ionizable gas, such as mercury or sodium vapor, emits visible radiation upon excitation typically caused by passage of current through the gas.
  • a medium to high pressure ionizable gas such as mercury or sodium vapor
  • One class of HID lamps comprises electrodeless lamps which generate an arc discharge by generating a solenoidal electric field in a high-pressure gaseous lamp fill.
  • the lamp fill, or discharge plasma is excited by radio frequency (RF) current in an excitation coil surrounding an arc tube.
  • RF radio frequency
  • the arc tube and excitation coil assembly acts essentially as a transformer which couples RF energy to the plasma. That is, the excitation coil acts as a primary coil, and the plasma functions as a single-turn secondary.
  • RF current in the excitation coil produces a time-varying magnetic field, in turn creating an electric field in the plasma which closes completely upon itself, i.e., a solenoidal electric field.
  • Current flows as a result of this electric field, resulting in a toroidal arc discharge in the arc tube.
  • the solenoidal electric field produced by the excitation coil is typically not high enough to ionize the gaseous fill and thus initiate the arc discharge.
  • One way to overcome this shortcoming is to lower the gas pressure of the fill, for example, by first immersing the arc tube in liquid nitrogen so that the gas temperature is decreased to a very low value and then allowing the gas temperature to increase. As the temperature rises, an optimum gas density is eventually reached for ionization, or breakdown, of the fill to occur so that an arc discharge is initiated.
  • the liquid nitrogen method of initiating an arc discharge is not practical for widespread commercial use.
  • More recent methods for starting electrodeless HID lamps entail using starting aids to capacitively couple the high voltage developed across the excitation coil turns into the arc tube. As a result of this voltage gradient, a capacitive current flows between the starting aid and the excitation coil, and hence through the arc tube, thereby ionizing the gaseous fill and producing a low current glow discharge therein. When the gas is sufficiently ionized, a transition is made from a relatively low current glow discharge to a relatively high current, high intensity solenoidal arc discharge.
  • a starting aid may comprise, for example, a pair of capacitive starting electrodes, as described in our U.S. Patent No. 4,902,937 (H.L.
  • Each starting electrode comprises a conductive ring which surrounds the arc tube and is connected to the excitation coil of the HID lamp. Coupling a high voltage signal between the pair of starting electrodes causes an electric field to be produced therebetween which is of sufficient magnitude to create a glow discharge in the arc tube due to the arc tube wall capacitance. Furthermore, as it has been determined that the application of relatively large fields directly to the arc tube via the starting aid may cause early arc tube degradation, heat sensitive members, e.g. bimetallic strips, are utilized for moving the starting electrodes away from the arc tube after initiating an arc discharge, thereby preserving the useful life of the lamp.
  • heat sensitive members e.g. bimetallic strips
  • a spiral starting electrode for an electrodeless HID lamp is described in our U.S. Patent No. 4,894,590 (H.L. Witting) the disclosure in which is also hereby incorporated by reference.
  • a single, conical-spiral-shaped starting electrode is positioned so that its narrower end is adjacent to, or on, the arc tube surface.
  • the wider end of the starting electrode is positioned so that flux generated by the excitation coil cuts the turns of the spiral electrode, thereby generating a high voltage signal which results in a sufficiently high electric field gradient to create a glow discharge in the arc tube.
  • a bimetallic strip is utilized to move the starting electrode away from the arc tube after an are discharge is initiated therein.
  • a starting aid for an electrodeless HID lamp which comprises a first conductive coil disposed about a second conductive coil, each coil having a truncated-cone shape.
  • the coils are wound in opposite directions so that voltages induced therein add together to provide a sufficiently high electric field gradient to initiate an arc discharge in the arc tube.
  • a bimetallic support is used to move the starting aid between a starting position adjacent to the arc tube and a lamp-operating position at a predetermined location away from the arc tube.
  • each of the hereinabove starting aids is effective in initiating an arc discharge in an electrodeless HID lamp, it may be desirable in some applications to improve the starting capability of an electrodeless HID lamp even further by easing the transition from low current glow discharge to high current, high intensity, solenoidal discharge.
  • a new and improved starting aid for an electrodeless HID lamp comprises a starting electrode disposed proximate the portion of the arc tube nearest the arc discharge to be initiated and oriented so as to provide a capacitive starting current that flows in substantially the same location as the arc discharge, thereby easing the transition from a relatively low current glow discharge to a high current, high intensity discharge.
  • the starting aid comprises at least one conductor which conforms to the arc tube and which is disposed adjacent thereto during initiation of the arc discharge and is thereafter moved to a predetermined location away from the arc tube.
  • the starting aid may comprise one or more fixed starting electrodes which likewise conform to the arc tube and are disposed adjacent thereto during initiation of the arc discharge.
  • a single starting electrode according to the present invention has a gap between the ends thereof which is of a size that is sufficiently large to avoid breakdown of gas between the ends of the conductor and between the electrode and the excitation coil (i.e. outside the arc tube), while still small enough to ensure breakdown of the fill within the arc tube.
  • the excitation coil i.e. outside the arc tube
  • the starting electrode configuration is such as to ensure breakdown of gas only within the arc tube of the lamp.
  • the starting electrode may have a gap between the ends thereof which is of a size that is sufficiently large to avoid breakdown of gas between the ends of the conductor and between the electrode and the excitation coil (i.e. outside the arc tube), while still small enough to ensure breakdown of the fill within the arc tube.
  • the ends of the conductors are separated by an amount that ensures breakdown of gas only within the arc tube.
  • the starting aid may be electrically coupled to the radio frequency power supply used to drive the lamp either directly, or via an impedance network, or via the excitation coil.
  • the starting aid may be coupled to a radio frequency starting circuit that is separate and independent from the radio frequency power supply used to drive the excitation coil of the HID lamp.
  • FIG. 1 illustrates an electrodeless HID lamp 10 employing a starting aid 12 in accordance with a preferred embodiment of the present invention.
  • Lamp 10 includes an arc tube 14 preferably formed of a high temperature glass, such as fused quartz, or an optically transparent ceramic, such as polycrystalline alumina.
  • An excitation coil 16 surrounds arc tube 14 and is coupled to a radio frequency (RF) ballast 18 for exciting a toroidal arc discharge 20 therein.
  • RF radio frequency
  • arc tube 14 is shown as having a substantially ellipsoid shape.
  • arc tubes of other shapes may be desirable, depending upon the application.
  • arc tube 14 may be spherical or may have the shape of a short cylinder, or "pillbox", having rounded edges, if desired.
  • Arc tube 14 contains a fill in which the arc discharge having a substantially toroidal shape is excited during lamp operation.
  • a suitable fill is described in our U.S. Patent No. 4,810,938 (P.D. Johnson, J.T. Dakin and J.M. Anderson) the disclosure in which is hereby incorporated by reference.
  • the fill of the Johnson et al. patent comprises a sodium halide, a cerium halide and xenon combined in weight proportions to generate visible radiation exhibiting high efficacy and good color rendering capability at while color temperatures.
  • such a fill according to the Johnson et al. patent may comprise sodium iodide and cerium chloride, in equal weight proportions, in combination with xenon at a partial pressure of about 500 torr.
  • a fill according to the Witting application may comprise a combination of lanthanum iodide, sodium iodide, cerium iodide, and 250 torr partial pressure of xenon.
  • Excitation coil 16 is illustrated as comprising a two-turn coil having a configuration such as that described in copending U.S. Patent Application of G.A. Farrall, Serial No. 493,266, and our corresponding DE application No. P4107263.4, the disclosures in which are hereby incorporated by reference.
  • Such a coil configuration results in very high efficiency and causes only minimal blockage of light from the lamp.
  • the overall shape of the excitation coil is generally that of a surface formed by rotating a bilaterally symmetrical trapezoid about a coil centre line situated in the same plane as the trapezoid, but which line does not intersect the trapezoid.
  • suitable coil configurations may be used with the starting aid of the present invention, such as that described in our U.S. Patent No. 4,812,702 (J.M. Anderson, the disclosure in which patent is hereby incorporated by reference.
  • the Anderson patent describes a coil having six turns which are arranged to have a substantially V-shaped cross section on each side of a coil center line.
  • Still another suitable excitation coil may be of solenoidal shape, for example.
  • RF current in coil 16 results in a time-varying magnetic field which produces within arc tube 14 an electric field that completely closes upon itself.
  • Current flows through the fill within arc tube 14 as a result of this solenoidal electric field, producing toroidal arc discharge 20 therein.
  • Suitable operating frequencies for RF ballast 18 are in the range from 0.1 to 30 megahertz (MHz), an exemplary operating frequency being 13.56 MHz.
  • Starting aid 12 is illustrated in Figure 1 as comprising a single electrode situated adjacent to the portion of arc tube 14 nearest the toroidal arc discharge during the initiation thereof.
  • the electrode preferably has a gap therein so as to avoid formation of a completed turn which would otherwise result in the existence of a secondary coil having a high circulating current therein.
  • starting aid 12 may comprise more than one suitably curved electrode of the same or different lengths, that are positioned with a gap therebetween (such as starting aids 30a-30b and 36a-36b of Figures 2 and 3, respectively).
  • the gap between the ends of one or more starting electrodes should be of a sufficiently large size so that breakdown does not occur between the ends of the electrodes or between the electrodes and the excitation coil.
  • a capacitive starting current is initiated in arc tube 14 which acts to ionize the gaseous fill therein, thus producing a relatively low current glow discharge.
  • the capacitive starting current is represented by arrows 22 in Figures 1B and 2.
  • the glow discharge transitions to a relatively high current, high intensity solenoidal arc discharge.
  • the capacitive starting current generated by the starting aid of the present invention flows in substantially the same location as the arc discharge, thus making the aforesaid transition easier and hence occur substantially instantaneously.
  • starting aid 12 in such close proximity to arc tube 14 during lamp starting, breakdown of the fill contained within arc tube 14 is ensured, while breakdown of any gas outside the arc tube is avoided.
  • starting electrode 12 may be moved to a predetermined location away from arc tube 14, if desired. In this way, starting electrode 12 does not substantially block light emission, interfere with the thermal balance of the arc tube, or contribute to arc tube degradation.
  • An electrode moving means 24 may comprise, for example, a heat sensitive support which is suitably curved at normal ambient temperatures to cause starting electrode 12 to lie adjacent to the surface of arc tube 14.
  • An exemplary heat sensitive support comprises a bimetal strip which undergoes differential expansion in response to the receipt of heat energy.
  • electrode moving means 24 comprises a piezoelectric bender responsive to an actuating DC voltage for moving the starting aid between the lamp-starting and lamp-operating positions.
  • the starting electrode is moved to the starting position adjacent to the arc tube.
  • the actuating voltage is reduced or removed once the arc discharge is initiated, and the starting electrode is moved back to its original position, i.e. the lamp-operating position.
  • a piezoelectric bender is described in U.S. Patent No. 4,894,589 (J.C. Borowiec) cited hereinabove.
  • FIG 3 illustrates an electrodeless HID lamp employing a starting aid 36a-36b in accordance with another preferred embodiment of the present invention wherein a starting circuit 32, which is separate and independent from RF ballast 18, is used to excite the starting aid.
  • arc tube 14 is preferably enclosed by an evacuated outer envelope 34, and excitation coil 16 surrounds the envelope in the vicinity of the arc tube.
  • the starting aid is illustrated as comprising two fixed, curved electrodes 36a and 36b of the same length situated on portions of arc tube 14 nearest arc discharge 20 and oriented to provide a capacitive starting current that flows in substantially the same location as the arc discharge, as described hereinabove. (However, it is to be understood that other starting aid configurations in accordance with the present invention, such as the those of Figures 1 and 2, may be employed with starting circuit 32 and with or without envelope 34.)
  • a suitable starting circuit is described in the S. A. El-Hamamsy and R. J. Thomas application cited at the beginning.
  • the starting circuit of that application comprises either a Class-D or Class-E power amplifier having an output resonant circuit tuned to a substantially higher frequency than the operating frequency of the signal provided to the excitation coil by the lamp ballast.
  • a suitable operating frequency for starting circuit 34 is 27.12 MHz.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Electromagnetism (AREA)
  • Circuit Arrangements For Discharge Lamps (AREA)
  • Discharge Lamps And Accessories Thereof (AREA)
EP19910304473 1990-05-23 1991-05-17 A starting aid for an electrodeless high intensity discharge lamp Withdrawn EP0458544A3 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US07/527,503 US5084654A (en) 1990-05-23 1990-05-23 Starting aid for an electrodeless high intensity discharge lamp
US527503 1990-05-23

Publications (2)

Publication Number Publication Date
EP0458544A2 true EP0458544A2 (fr) 1991-11-27
EP0458544A3 EP0458544A3 (en) 1992-05-27

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Family Applications (1)

Application Number Title Priority Date Filing Date
EP19910304473 Withdrawn EP0458544A3 (en) 1990-05-23 1991-05-17 A starting aid for an electrodeless high intensity discharge lamp

Country Status (4)

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US (1) US5084654A (fr)
EP (1) EP0458544A3 (fr)
JP (1) JPH04229549A (fr)
AU (1) AU637216B2 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0602746A1 (fr) * 1992-12-15 1994-06-22 Matsushita Electric Works, Ltd. Lampe à décharge sans électrodes
EP1414058A3 (fr) * 2002-10-24 2006-02-15 Lg Electronics Inc. Système de lampe sans électrodes et ampoule pour celui-ci
US7253555B2 (en) 2002-10-24 2007-08-07 Lg Electronics Inc. Electrodeless lamp system and bulb thereof

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5059868A (en) * 1990-05-23 1991-10-22 General Electric Company Starting circuit for an electrodeless high intensity discharge lamp
US5047693A (en) * 1990-05-23 1991-09-10 General Electric Company Starting aid for an electrodeless high intensity discharge lamp
JPH0727774B2 (ja) * 1990-10-26 1995-03-29 松下電工株式会社 無電極放電ランプ
DE69206921T2 (de) * 1991-08-14 1996-07-04 Matsushita Electric Works Ltd Elektrodenlose Entladungslampe
JPH0611254U (ja) * 1992-07-15 1994-02-10 松下電工株式会社 無電極放電灯
US5619103A (en) * 1993-11-02 1997-04-08 Wisconsin Alumni Research Foundation Inductively coupled plasma generating devices
US5838108A (en) * 1996-08-14 1998-11-17 Fusion Uv Systems, Inc. Method and apparatus for starting difficult to start electrodeless lamps using a field emission source

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4783615A (en) * 1985-06-26 1988-11-08 General Electric Company Electrodeless high pressure sodium iodide arc lamp
US4959582A (en) * 1986-08-28 1990-09-25 Imago Quaestus, Inc. Video storage cabinet
US4810938A (en) * 1987-10-01 1989-03-07 General Electric Company High efficacy electrodeless high intensity discharge lamp
US4812702A (en) * 1987-12-28 1989-03-14 General Electric Company Excitation coil for hid electrodeless discharge lamp
US4902937A (en) * 1988-07-28 1990-02-20 General Electric Company Capacitive starting electrodes for hid lamps
US4894590A (en) * 1988-08-01 1990-01-16 General Electric Company Spiral single starting electrode for HID lamps
US4894589A (en) * 1988-08-08 1990-01-16 General Electric Company Starting means, with piezoelectrically-located capacitive starting electrodes, for HID lamps
US4982140A (en) * 1989-10-05 1991-01-01 General Electric Company Starting aid for an electrodeless high intensity discharge lamp
US5047693A (en) * 1990-05-23 1991-09-10 General Electric Company Starting aid for an electrodeless high intensity discharge lamp

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0602746A1 (fr) * 1992-12-15 1994-06-22 Matsushita Electric Works, Ltd. Lampe à décharge sans électrodes
EP0698914B1 (fr) * 1992-12-15 1999-03-17 Matsushita Electric Works, Ltd. Lampe à décharge sans électrodes
CN1055782C (zh) * 1992-12-15 2000-08-23 松下电工株式会社 无电极放电灯
EP1414058A3 (fr) * 2002-10-24 2006-02-15 Lg Electronics Inc. Système de lampe sans électrodes et ampoule pour celui-ci
US7253555B2 (en) 2002-10-24 2007-08-07 Lg Electronics Inc. Electrodeless lamp system and bulb thereof

Also Published As

Publication number Publication date
AU7514391A (en) 1991-11-28
AU637216B2 (en) 1993-05-20
JPH04229549A (ja) 1992-08-19
EP0458544A3 (en) 1992-05-27
US5084654A (en) 1992-01-28

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